Anisotropic cellular structures from semi‐crystalline polymer templates

Abstract

We report an investigation to determine the effect of an anisotropic semicrystalline template on the resulting cell morphology of microcellular polymeric foams generated in these materials. Poly(ethylene terephthalate) (PET)-polystyrene (PS) composite foams are prepared by using supercritical carbon dioxide (scCO 2) not only as a foaming agent but also as a transport medium of styrene and initiator into a biaxially-oriented PET templating film. The composite foam so obtained demonstrates a highly interpenetrating network verified by a single Tg of 98 C. Substrate orientation is observed not to dictate the cell formation; however highly anisotropic swelling and a shapetemplating phenomenon is observed, with the most significant dimension change in the thickness of the film. Introducing confinement in the direction of maximum dimension change is found to introduce a highly anisotropic lamellar cell architecture.

Anisotropic solid-state PLA foaming templated by crystal phase pre-oriented with 3D printing: cell supporting structures with directional capillary transfer function

“…S5A–C, ESI†). Remarkably, the anisotropic microporosity did not descend exclusively from external confinement like in the previous study 26 because it was also present in the unconfined sample (Fig. S5D, ESI†).…”

“…(D) Dichroic ratio defined by the ratio of absorbance measured with polarizers set to 901 and 01, the peaks at 918 and 956 cm À1 corresponded to the crystalline and amorphous phase, respectively. 27 microporosity did not descend exclusively from external confinement like in the previous study 26 because it was also present in the unconfined sample (Fig. S5D, ESI †).…”

“…24,25 Among them, one has attempted to use an anisotropic semicrystalline substrate with a second amorphous phase as a template for highly oriented cell growth. 26 Nevertheless, there was presumably no contribution of the semicrystalline template observed since these foams showed little anisotropy unless an additional external confinement helping to orient the growing cells was imposed upon the foaming.…”

Morphology and Compressive Properties of Extruded Polyethylene Terephthalate Foam

“…Polymer foams are commonly used in various industries, including packaging, construction, wind turbine blades, automotive, and aerospace industries, due to their numerous advantages. These include their controllability, abundance of raw materials, affordability, high specific strength and modulus, thermal insulation, impact resistance, and noise reduction capabilities [ 1 , 2 , 3 ]. Polyethylene terephthalate (PET) foam has several advantages, including a non-toxic manufacturing process, easy recyclability, high heat deflection temperature, relatively good mechanical performance, and lower cost raw materials, or the use of recycled PET material.…”

“…The relationship between the morphology and mechanical properties of polymeric foams such as PVC, polyurethane (PU), and polypropylene (PP) has been extensively studied [ 3 , 8 , 9 , 10 , 23 , 24 , 39 , 40 ]. The mechanical properties of PET foam in relation to its morphology have been little studied.…”